The subject matter discussed in the background section should not be assumed to be prior art merely as a result of its mention in the background section. Similarly, a problem mentioned in the background section or associated with the subject matter of the background section should not be assumed to have been previously recognized in the prior art. The subject matter in the background section merely represents different approaches, which in and of themselves may also correspond to claimed embodiments.
A Network-Network Interconnect (NNI) is a connection between two network domains, each operated independently under different network management and administration. Sometimes the term NNI is used exclusively for interconnections between two different service provider networks, and the term User-Network Interface (UNI) is used for interconnections between a customer or subscriber and a service provider network. This document makes reference to the term NNI to include both cases.
Maintaining high availability of an NNI is of paramount importance to network operators. So as to maximize availability (e.g., uptime, fault tolerance, etc.), NNIs are sometimes constructed using redundant nodes (such as switches or bridges) and redundant links, so that the NNI is capable of withstanding a failure of either a node or a link. In other instances, a network operator may use a same set of nodes to create NNIs to two or more other networks, thus having shared nodes (e.g., overlapping nodes or nodes that are common to more than one NNI) in the construction of an NNI in order to improve the resilience and fault tolerant capabilities of the constructed NNI.
Routing and forwarding problems arise when implementing NNI network topologies for connecting distinct networks (e.g., disparate network providers, user networks, and/or network operators). For example, depending on the chosen implementation, it may be required that an ISC link be active on a particular network, a requirement that may be in conflict with a network operator's own requirements or chosen topology. Alternatively, it may be necessary to “tag” incoming and outgoing frames, identifying the frame as being associated with local traffic or with a specific NNI (e.g., by “tagging” or “encapsulating” the frames), however, as is well understood by those having skill in the art, any tagging or frame encapsulation scheme either creates a significant network bottleneck or requires costly dedicated hardware solutions capable of performing the tagging or frame encapsulation scheme with enough speed to obviate the bottleneck. For these reasons, tagging and/or frame encapsulation schemes are sometimes undesirable.
Improved mechanisms for forwarding networking frames (e.g., packets) within a network topology having one or more Network-to-Network Interconnects (NNIs) between separate and distinct networks (e.g., one or more NNIs between two or more networks having separate and distinct management and administration) is therefore desirable. Solutions to the above mentioned problems and other benefits of Applicants' disclosed embodiments are described in additional detail below.